#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<string>
using namespace std;
int main() {
	string s;
	string s1, s2;
	int n;
	cin >> n;
	cin >> s1 >> s2;
	int prev1 = -1, prev2 = -1, ret = 0x3f3f3f3f;
	for (int i = 0; i < n; i++)
	{
		cin >> s;
		if (s == s1) {
			if (prev2 != -1)
			{
				ret = min(ret, i - prev2);
			}prev1 = i;
		}if (s == s2) {
			if (prev1 != -1)
			{
				ret = min(ret, i - prev1);
			}prev2 = i;
		}
	}
	if (ret == 0x3f3f3f3f)cout << -1 << endl;
	else cout << ret << endl;
	return 0;
}